【作者】 侯士敏；

【Author】 Shimin Hou;Department of Electronic, Peking University;

【机构】 北京大学信息科学技术学院；

【摘要】 分子电子学是解决硅基微电子器件小型化难题最有希望的方案之一,氢单分子结则是结构最为简单的分子电子器件。我们利用非平衡格林函数与密度泛函理论相结合方法研究了Cu-H₂-Cu和Au-H₂-Au单分子结的原子构型和电子输运性质。计算结果表明,当H₂分子与Cu电极形成非对称结构的单分子结时,其低偏压电导和分子振动频率的理论计算值与实验测量结果相一致,揭示出分子-电极界面结构对分子结电子输运性质的重要影响;H₂分子在Au单原子链上分解成两个H原子并形成双桥位吸附结构,其低偏压电导曲线和分子振动频率的计算结果与实验测量结果相符合,解释了在氢气环境中形成的金接触结构的分子振动与电子输运性质。最后我们以Au-H₂-Au单分子结为例研究了分子结中电流诱导的声子振动频率的重整化问题。更多还原

【Abstract】 The electronic transport properties of Cu-H₂-Cu and Au-H₂-Au single-molecule junctions are investigated by employing the nonequilibrium Green’s function formalism combined with density functional theory. Our calculations show that, when one H₂ molecule asymmetrically binds to the two Cu electrodes, the calculated values of the low-bias conductance and the vibrational frequencies are in good agreement with the measured ones, illustrating the significant effects of the molecule-electrode interfaces on electron transport. In contrast, hydrogen molecules can dissociate on stretched gold monatomic chains and form an Au-H-Au-H-Au double-bridge structure, the low-bias conductance curve and the vibrational frequencies are consistent with the experimental result, providing an explanation to the observed vibrational and electronic transport properties of gold atomic junctions in hydrogen environment. Furthermore, we investigate current induced phonons renormalization in molecular junctions using the Au-H₂-Au junction as an example.更多还原